Telephone system



pri 26, 1932. c. E, BEALE ET AL. 1,855,701

TELEPHONE SYSTEM Filed Jur-1e 15, 195o s sheets-Sheet 1 TO UNE BUZZED?To CONN. BNKS p 25, i932 C. E.- BEALE ET AL. 1,855,701

TELEPHONE SYSTEM Filed June 13, 1930 3 Sheets-Sheet 2 Imm-'s' .Ehm-lasEdmund Beale Herb''ilay 575555 TELEPHONE SYSTEM Filed June l5, 1930 l C5Sheets-Sheet 3 TO TO LINE RELAY NIGHTLINE TO MAIN EXCHANGE DDI -v r TTZ5 T0 LINE RELAYS Patented Apr. 26, 1932 UNITED STATES PATENT OFFICECHARLES EDMUN D IBEALE AND HERBERT STANLEY DEYES, F LIVERPOOL, ENGLAND,ASSIGNORS T0 ASSOCIATED TELEPHONE AND TELEGRAPH COMPANY, 0F CHICAGO,ILLINOIS, A CORPURATION OF DELAWARE TELEPHONE SYSTEM Application ledJune 13, 1930, Serial No. 461,026, and in Great Britain June 25, 1929.

The present invention relates to telephone systems and 1s morepartlcularly concerned single motion rotary stepy-step switches having acapacity in the examples given of 22 local lines. Subscribers havingaccess to both local lines and main exchange. lilies are provided withtwo pairs of speaking conductors, and these are preferably connected tothe same instrument which may be of the type described in the Stehlikapplication, Serial No.

400.402, filed 17th October, 1929. This type of instrument is providedwith keys whereby it may be connected to either of the pairs otconductors dependent upon whether the call is a local call or a callnecessitating connection at the main exchange. v

One feature of the invention relates to a telephone systcmin which callslocal to the branch exchange are set up by the subscriber over one linewhile calls to and from the main exchange are set up over a further linebyiineans of an automatic switch which is adapted to operate as a finderswitch or as a connector switch dependent upon whether thc calls are toor from the main exchange.

A further feature. of the invention relates to a telephone system inwhich connections local to the branch exchange are set up by the callingparty over a finder switch and a connector switch and outgoing callsfrom the branch exchange to the main exchange are set up by thesubscriber over a. further finder switch which is taken into use. over asep arate line. while incoming calls from the main exchange to thebranch exchange are set up by an operator who directively controls thesaid further finder switch to connect with the wanted line.

A still further feature ot the inventionl relates to a telephone systemhaving connections from the main exchange to the branch exchange set upbv an operator over an automatic switch in which when the operator setsup a. connection and the called subscriber is busy the performance of aspecial manual operation by the operator serves to hold the callingsubscriber-s line and causes the wanted sbbscrlwr to be automaticallyrung when lie replaces his receiver at the end of his conversation andto be switched throughto the calling subscriber at the main exchangewhen he again lifts his receiver.

lu order that t-he invention ma be better understood, the followingdescrlption will now be. given of one method of carrying it into effectwhich should be taken in conjunction with the accompanying drawings, andit willbe understood that thls is given by way of example only, and thatvarious modifications may be made in the circuit details by thoseskilled in the art without departing from the spirit of the invention.

Referring now to the drawings, Fig. 1 shows a finder and connector link,by means ot which local calls are established, while Figs. 2 and 3 showthe apparatus which is taken into use over the second set of conductors,and which establishes connections to and from the main exchange.

Referring now more particularly to Fig. 1, when the subscriber removeshis receiver prior to setting up a. local call, relay LK will beenergized over the circuit, earth at armature Z103, conductor 10,circuit via the calling subscribers instrument, conductor 11, restingcontacts of armature Z104, left hand winding of relay LK via the windingof the common start relay S to battery. Bela S is operated fully inthiscircuit while re ay LK is operated only partially, and suicient to makeits light armature Z101, whereupon a marking circuit may be traced tothe bank of the tinder switch FS from earth at armature s1, operatedarmature Zkl, resting contacts of armature M2 to the associated bankcontact, and moreover, a parallel circuit may be traced by way ofresting contacts of armature b4, and armature (Z2, left-hand winding ofrelay G, interrupter springs fdm, of finder switch driving magnet FDM tobattery by way of the resistance 12. Relay G thereupon operates over thecircuit described and completes a circuit from earth at the restingcontacts of armature b5, operated armature g2, winding of the finderswitch driving magnet FDM to battery. The magnet thereupon energizes ipreparatory to advancing the wipers of the finder switch FS one step,and when the interrupter springs fdm are operated the circuit of relay Gis opened and this relay releases and in turn o ens the energizing`circuit to the magnet F M, so that the latter de-energizes and advancesthe wipers to the next set of bank contacts. Inter-action between relayG and the finder switch driving magnet FDM will cause the wipers of thatswitch to be advanced in search of the calling bank contacts which itwill be remembered were marked by the connection of earth potentialthereto. When these marked contacts are reached, relay G will beprevented from again operating due to the short-circuiting earth whichis now encountered by the test-ing wiper P1, and the wipers of theswitch are held in this posit-ion.

No further circuit changes now take place until the wipers of theconnector switch CS arrive at the home position, whereupon relay E willbe operated in a circuit which includes earth at the operated armatures1 of the start relay, resting contacts of armatures b4 and d2,right-hand winding of relay E, home bank contacts andwiper H,interrupter springs edm, and winding of the connector switch drivingmagnet CDM to battery. Relay E accordingly operates in the circuitdescribed and at armature el prepares the impulsing circuit to theconnector switch driving magnet iCDM, at armature e2 extends earth fromthe wiper Pl, via the resting contacts of armature b3 to the lowerwinding of relay A to battery, and finally at armature e4 prepares acircuit to the righthand winding of the interrupt-er and busy test relayG. Relay A in operating over its lower winding at armature a1 completesthe circuit to the guard relay B which also operates. Relay B atarmature b1 prepares a further point in the connector switch steppingcircuit, at armatures b2 and b3 connects up the positive and negativewipers of the finder switch FS to the impulse accepting relay A, atarmature b4 extends the common start lead on :to the next linderconnector switch circuit, and at armature b5 prepares various lockingcircuits and extends earth via the wiper P and bank contact to theright-hand coil of the subscribers line relay LK. Relay LK thereuponfully operates in order to clear the calling line of its normal batteryand earth connections at armatures .2k3 and Zit-4, and at armature c2removes the marking potential from the associated P1 bank contact. Thejumpering block 32 is provided in order that all unused contacts of theswitch FS can be earthed. Dial tone from conductor 16 is now extendedover the positive wiper of the switch CS and the circuit is prepared forthe reception of the dial impulses from the subscribers calling device,upon the reception of which relay A will impulse in synchronism therto.Relay A at armature al will repeat these impulses over a circuit whichincludes, the operated armature b1, resting contacts of armatures 71.5and g1, low resistance lefthand coil of relay E, winding of theconnector switch driving magnet CDM to battery. The wipers of theconnector switch CS are accordingly advanced the appropriate number ofsteps into engagement with the contacts of the desired line, and it willbe appreciated that owing to the copper slug which surrounds the core ofrelay B, this relay will be maintained operated during the impulsingperiod, while in a similar manner relay E will also be held operated, soas to extend the right-hand winding of relay G to the testing wiper P ofthe connector switch CS.

In case the desired subscriber should be busy at this time, wiper P willencounter earth on the associated bank contact and during the slowrelease period of relay E, this earth will be extended to the right-handwinding of relay G, thereby causing this relay to operate and when relayE eventually releases, relay G will then lock up over the circuit, earthat the operated armature b5, operated armature g3, resting contactsassociated with armature e4, winding of relay Gto battery. Relay G inoperating, at armature g1 opens the impulsing circuit to prevent anyfurther impulses being received b the connector switch driving magnetCDL at armature g2 prepares a homing circuit to theflnder switch drivingmagnetFDM which is not effective at this stage, and at armature g4extends busy tone over conductor 13, resting contacts of armature c3,the posit-ive speaking conductor to the calling subscriber, therebyproducing an audible signal in the calling subscriber-s receiver toindicate that the required subscriber is busy.

If, however the calling line is idle at this time, Wiper P will notencounter earth on the associated bank contact so that relay G will notbe operated, and when relay E finally releases after its lslow period acircuit may be traced from earth at armature b5, resting contacts ofarmature g3, lower winding of relay H, resting contacts of armature e4,wiper P of switch CS and bank contact to battery via the winding of thecalled subscribers line relay. The called subscribers` line relay andrelay H are therefore operated in series over this circuit, the formerclearing the called subscribers line of the normal battery and earthconnections, while the latter relay completes a circuit by way of itslight armature h1, its upper locking winding to battery. Relay H istherefore fully operated over this latter circuit and at armature h2extends direct earth to the wiper P of switch CS in order to guard theconnection and hold operated the called subscribers line relay, atarmature h5 opens a 'place between the two point in the stepping circuitto the connector switch driving magnet CDM and at armatures k3 and h4completes a circuit to ring the called subscribers bell which may betx'aced vfrom ringing current over conductor 14, left-hand winding ofthe ring trip relay F, armature f2, armature h3, positive wiper and bankcontact of switch CS, called subscribers circuit, bank contact andnegative wiper of switch CS, armature h4, to earth at armature f4. T hecalled subscribers bell is therefore rung inthe usual manner and anaudible signal to this effect is provided to the calling subscriber overa leak on the main ringing circuit by way of the low capacity condenserQ, resting contacts of armatures g4 and e3, the positive speakingconductor to the calling subscriber.

When the called subscriber replies the direct current circuit thereuponcompleted, causes ring trip relay F to be operated so that it locks byway of its light armature f1 to earth at armature b5, while at armaturef3 it opens the circuit which extends to the Y fuse alarm bell, overconductor 30, and at armature f2 and f4 completes the transmissioncircuit between the two subscribers instruments.

Owing to the operation of relay F a circuit is completed for relay Dwhich operates and at armature Z1 closes a point in the circuit of thefuse alarm bell. The fuse alarm bell will not be operated as its circuitwill be open at armature f3. This bell is only operated when a fuseblows as battery is then connected up from the fuse alarm stud overconductor 31 to the upper winding of relay I). This relay thereuponoperates and at armature d, closes the circuit to the fuse alarm bell asrelay F is not operated at this time.

Owing to the operation of relay F as mentioned above, conversation maynow take subscribers, and at its conclusion when the calling subscriberhangs up his telephone, relay A releases and is followed shortlyafterwards by relay B which is in turn followed by relays l", H and LK.

Consequent upon the release of relay B a homing circuit may be traced tothe connector switch CS from earth at the resting contacts of armaturesb5 and e5, bank conimoning and wiper H, interrnpter springs calm,winding of driving magnet CDM to battery. The connector switch drivingmagnet CDM is accordingly energized in a selfinterrupted circuit untilwiper H is advanced to the home position, that is, out of engagementwith the bank commoning and it will be noticed as mentioned previouslyin the description, relay E cannot again operate to complete the dialstepping circuit until this home position is reached.

It should also be mentioned that the numbers of the subscribers may beany of the following, 1--9, 0l--09, G01-004. This arrangement isv madepossible by leaving the 10th and 20th sets of contacts unwired so thatif, for example, 0 is dialled as a first digit the switch will beadvanced in the manner described so that the wipers come to rest on the10th set of bank contacts, and since wiper P does not encounter eitherearth or battery the switching operations will be suspended, and uponthe reception of further trains of impulses the wipers of the switchmaybe set on any of the succeeding line contacts, or similarly if a further10 impulses are transmitted the switching operations will again besuspended until the reception of the third digit which will set thewipers of the switch on one of the remaining contacts.

Referring now to Figs. 2 and 3 which show the equipment provided to giveout-service, it will be seen that Fig. 2 shows a combined finder andconnector switch FCS, while Fig. 3 shows the equipment at the attendantscabinet. When a subscriber wishes to originate a main exchange call helifts his receiver in order to complete a circuit across conductors l0and 11 so that relays LK and ST are operated in series in a mannersimilar to that described in connection with Fig. 1, and it will be seenthat the former in operating its light armature Usl, only, prepares amarking on the appropriate bank contact, of the switch FCS, while theoperation of the common start relay ST completes the following circuit,earth at armature stl, resting contactsA of armatures Z3, h3, b3,interrupter springs fem, left-hand coil of relay FY to battery via theresistance 12. Similarly a parallel circuit may also be traced by way ofthe resting contacts of armatures 21, 005, and h6, right hand coil ofrelay F to battery so that this latter relay operated and at itsarmature f1 prepares a locking circuit which will become effective at alater.period, and at armatures f4 and f5 prepares points in the speakingcircuit. Upon the operation of rclay FY over the circuit previouslytraced, earth at the resting contacts of armature b1 will then beextended by way of armature 11.7, operated armature f i/B, restingcontacts of armature 22, winding of the tinderconnector switch drivingmagnet FCM to battery, and in parallel thereto via the right-hand coilof relay E to battery. The magnet FCM is thereupon energized in thiscircuit in order to prepare the stepping the wipers of the switch FCS onto the next set of bank contacts, and upon the full operation of themagnet FCM the holding circuit to relay FY is opened at the interruptersprings fom,

so that the latter relay releases and in turnl opens the energizingcircuit to the magnet FCM at armature ffl/3. Upon the de-encrgization ofthe magnet FCM the associated wipers are advanced on to the next set ofbank contacts, and when this has been done, springs fom will again makecontact thereby lili re-operating relay FY. Inter-action between relayFY and the magnet FCM wlll result in the wipers of the switch FCS beingautomatically rotated in search of the marked bank contact, and sincerelay is operated in parallel'with the magnet c1rcu1t and 1s equippedwith a copper slug 1t remains operated throughout the stepping period.Re-` lay E at armut-ure e1 connects up an alarm circuit which is withouteffect at this time, at armature e2 prepares a circuit to relay G, andat armatures e3 and e4 disconnects the negative and positive wipers sothat the apparatus will not be influenced by potentlal picked up onthese wipers during thelr rotation to the marked line. lVhen the markedline is reached relay FY will not again be operated due to theshort-circuiting earth encountered by wiper P1, so that the wipers willbe held in this position and relay B will be operated from earth appliedat the operated armature f3. Relay B in operating, at armature b1prepares various holding circuits, at armature b2 prepares a circuit tothe pilot lamp PL, at the attendants cabinet and at armature b3 connectsthe common start lead onto the next finder connector switch. Upon therelease of relay E at the end of the 1mpulsing period, the followingcircuit is completed to relay H, from earth at armature 1, armature g1,lower winding of relay H, armature e2, wiper P and bank contact, tobattery via the right-hand coil of the line relay LK. Relays LK and Hare thereupon operated in series, the former at armatures M3 and M24clearing the calling line of the normal battery and earth connections,while the latter at its light armature k1 completes a locking circuit toits other locking winding. Relay H then fully operates and at armatureh2 connects direct earth to the wiper P in order to guard the connectionand hold operated the line relay LK, at armatures Il?) and h4 completesthe circuit to the main exchange, atV armature h5 prepares a circuit torelay FY, at armature h6 transfers the holding circuit to relay F by wayof its own armature f1, and at armature k7 opens a further point in thestepping circuit to the magnet FCM. The speaking circuit is nowcompleted to the main exchange, and includes relay A; this relaytherefore operates and at armature al maintains the holding circuit torelay B on its right-hand coil since the left-hand coil is disconnectedupon the full operation of the line relay LK.

No further circuit changes now take place until the operator at the mainexchange answers the call, and in case the connection should be to anautomatic exchange the subscriber will receive the dial tone from theswitch taken into use therea-t, and will then proceed to transmit thedigits of the required subscribers number by way of the coil of relay Awhich has been bridged by a condenser and a non-inductive resistance soas to offer a low impedance to the impulse train. It will be notedduring the speaking condition that relays H and 'F are held o erateddependent on relay B, while relay is in turn dependent upon relay A, andis equipped with a copper slug so as to remain operated during theimpulsing period. Since in the example described it is desirable that atthe end of the conversation the switch should be returned to a homeposition, the circuit for effecting this will now be described.

lVhen the calling subscriber hangs up his receiver at the conclusion ofthe conversation, relay A will release owing to the opening of the loopcircuit and is followed shortly afterwards by relays B, F, H and LK.Relay LK in releasing extends earth at ar1nature M3 by way of the bankcontact and positive wiper, resting contacts of armatures e3 h3, 006 andhar/5, lower winding of relay Z to battery. Relay Z thereupon operatesin the circuit described and at armature z3 connects earth to mark thehome bank contact of the switch FCS. at armature e2 removes theshort-circuit off the upper winding of relay Z. and finally at armature21 extends earth from the resting contacts of armature b1, operatedarmature a1, interrupter springs fom. left-hand'coil of relay FY tobattery via the resistance 12. Relay FY thereupon operates and atarmature ffl/3 extends earth from the resting contacts of armature b1,armature la7, armature ffy/3, low resistance upper windingI of relay Z,winding of the driving magnet FCM to batterv. Relay FY and the drivingmagnet FCM thereupon inter-act in order to advance the wipers into thehome position and it will be noticed when the circuit is opened to thelower winding of relay Z when the wipers make the first step, this relayremains operated over its upper winding in series with the driving'magnet FCM during the automatic rotation of the switch. Moreover relay Eis also operated in a parallel circuit. in order to disconnect thenegative and positive wipers during the homing operation at armatures e3and e4. while the private wiper is disconnected at armature 24. Althoughit will be seen from the drawings that relays HX and LC are alsooperated during this homing period. these operations are withoutfunction at this stage. When wiper P1 encounters the home bank contactwhich is marked by the connection of earth thereto via armature z3.relav FY cannot again be operated so that the wipers are held in thisposition. whereupon relays Z. HX and E restore after their slow periodand finally relay LC also releases. so that the circuit is now preparedfor use by other calling subscribers. A description will now be given ofthe circuit operations which take place on an incoming call. Relay L isoperated from ringing current over the circuit from conductor A, restingcontacts of night switch key NS, conductor 15, right-hand coil of relayL, condenser Q, conductor 1G, other resting springs of night switchingkey NS, conductor B to the main exchange. Relay L thereupon opcrates itslight armature Z1 in order to complete a locking circuit to itsleft-hand locking winding from earth at the resting contacts of armatureb1, resting contacts of armature X01, operated armature Z1, winding ofrelay L to battery. Relay L then fully operates and at armature Z3switches the start lead on to A the next finder connector switch. Aparallel circuit may also be traced from armature Z1, by way of theresting contacts of armature )c3/2, over conductor 17, to light thepilot lamp PL associated with the calling line at the attendantscabinet. The operator on seeing the lamp li ht thereupon operates theanswering key A S, in order to connect her telephone circuit across thecalling line so as to enable her to receive the request from thecallingsubscriber. The operation of the answering key ANS at a pair of springslocated in the lower half of the drawing extends earth over conductor18, to operate relay LC, sol that the latter relay then at armature Z02prepares an operating circuit for relay H and at armature Z01 opens thelocking circuit of the calling relay L, which however, d oes not releaseowing to its right-hand winding being now energized over a circuitextending from earth, upper winding of the retard R,

springs of key SD, springs of key ANS, con-y ductor 15, right-handwinding of relay L, short-circuiting springs of the key AN S', springsof the key ANS, springs of the key SD, lower winding of the retard R tobatter Vihen the operator has ascertained the wanted subscribers numbershe will then operate the so-called speak and dial key SD which connectsher telephone circuit on to the calling side of circuit andshort-circuits the condenser Q so as to hold relay L, and also at alower set of springs extends earth from the answering key over conductor19 to operate relay OC;l Relay OC operates and at its armatures 001 and002' prepares points in the speaking circuit for the operator which willbecome effective in case the wanted subscriber tests busy, at armature003 prepares an impulsing circuit to the driving magnet FCM, at armature00.4 completes a. circuit to the impulsing relay IP which may be. tracedfrom earth at the resting contacts of the local call key CL (Fig. 3)resting springs of the dial DD, conductor 20, armature 004, conductor21, winding of relay IP to battery, at armature 005 opens a point in thecircuit to relay F, at armature 006 disconnects relay Z from thepositive wiper of the switch FCS and at armature 007 opens a point vinthe alarm circuit.

.resting contacts of armature z'pl, conductor 22, operated armature 003,right-hand coil of relay tobattery, and in parallel thereto via theresting armature z2 and the winding of the driving magnet F CM tobattery. The intermittentoperation of the driving mag-2.

net F CM causes the wipers of the switch j' FCS to be advanced intoengagement with the desired bank contact, and as the relay E is alsooperated in a parallel circuit, the positive and negative wipers aredisconnected at armatures e3 and e4 during the rotation, and at armaturee2 a circuit is prepared for the busy test relay G. If now the wantedline is idle when the wipers encounter the associated bank contact,relay E will be released after its slow period and circuit will then becompleted for the operation of the switching relay H from earth atarmature 23, operated armature Z02, armature g1, lower winding of relayH, armature e2, wiper P and bank contact, winding of the calledsubscribers line relay LK to battery. Relays LK and H are thereuponoperated in series, the former the light armature hl, and upon the fulloperation of the relay over this latter circuit,

ringing current will then be extended to the called subscribersinstrument over the circuit, ringing current connected to conductor 23,winding of relay F, armatures f5, 124, and e4, negative wiper, and bankcontact, conductor 11, circuit via the called subscribers instrument,conductor 10, bank contact and positive wiper, armatures 03, 'h3 and f4t0 earth. The called subscribers bell is thereupon rung in the usualmanner and when he replies a direct current circuit completed throughthe instrument causes relay F to operate and lock by way of itsright-hand locking` coil, thereby at armatures f4 and f5 completing thespeaking circuit to the calling subscriber. I nder these conditions theoperator will then restore her keys to normal and permit theconversation to proceed.

If, however, the wanted subscriber is busy` when his lines are connectedwith, wiper P will then encounter earth so that during the slow releaseperiod of relay E, relay G is' operated and at its armature g2 maintainsa at armature g6 connects a low tone by way of the condenser Q2 to thenegative speaking conductor in order to inform the subscriber that theopera-tor is on the line and wishes to offer a call. If the busySubscriber agrees to take the call immediately, the operator willrequest both subscribers to replac'e their telephones on the switchhooks, and when this is done relay LK will be released and earth will beremoved from the bank contact associated with wiper P, whereupon relay Greleases and relay H is permitted to operate in the usual manner frombatat the resting contacts of armature b1. Re-

lay HX in operating at arma-ture km2, maintams relay LC, at armature uvconnects the common start lead to the next nder connector switch, atarmature kwa maintains relay L over a circuit extending from battery viathe main exchange equipment and at armature 11.025 opens a point in thecircuit to the lower Winding of relay Z.

The operator may now restore her answering and dial keys and the circuitwill be` held in the above condition until the busy subscriber hasfinished his conversation. When the busy subscriber replaces histelephone on the switch hook at the end of his conversation relay G willrelease as previousl explained and relay H will extend ringing currentto the said subscribers instrument circuit, and although the release ofrelay G opens the holding circuit to relay HX, the operation of relay Hat armature la7 maintains relay HX in an operated condition. When theWanted subscriber replies, relay F operates and connects the speakingcircuit through and upon the operation of rela A, relay i3 will operateand open the holdiing circuit to relay HX, which will accordmgly releasetogether with the other relays which were held over circuits includingits operated contacts.

In case the operator desires to originate a call to the main oiiice 'shewill operate the local call key CL, thereby completing a circuit overconductors 25 and 26 which extend to a line relay such as LK and thebanks of the linder connector switch FCS over the circuit, conductor 25,operated contacts of key CL, resting contacts of dial impulse springs,to other operated contacts of key CL,'via further operated contacts ofkey CL, Windsprings DDl of the dial, .in order to prevent o n telephonereceiver.

During night periods, the night switching key NS is operated, and sincea particular clicks beino heard by the operator in the subscriberstelephone line is connected by Way of the resting contacts of this key,the normal circuit will be disconnected from the P. A. X. equipment, andat the operated springs of the key the main exchange line will beextended direct to the subscribers instrument. By this arrangement callsincoming from the main exchange during night periods will be receiveddirect on this particular subscribers instrument .which might be forexample, located at the night watchmans premises.

We claim l. In a telephone system, amain exchange and a branch exchangeconnected by a trunk line, a subscribers station connected with thebranch exchange over two separate lines, local switching apparatusco-operating with one of said lines for establishing connections betweensaid station and other branch exchange stations, an automatic switchterminating said trunk line at the branch exchange, means controlled bythe subscriber at said station oven, the other of said lines foroperating said switch as a finder to establish a connection with saidtrunk line, and

means effective on lan incoming call over the trunk line for directivelyoperating said switch as a connector to establish a connection with saidstation via the other of said lines.

2. In a telephone system, a main exchange and a branch exchangeconnected by a trunk line, a subscribers station connected with thebranch exchange by two separate lines, an attendants switchboard at thebranch exchange, local switching apparatus co-operating with one of saidlines for establishing connections between said stationand other branchexchange stations, an automatic switch terminating said trunk` line atthe branch exchange, means Vcontrolled by the subscriber at said stationover the other of said lines for operating said switch as a finder toestablish a connection with saidV trunk line, and means controlled fromsaid switchboard for directively operating said switch to extend anincoming call over the 1 trunk line to said station via said other line.3. In a telephone system, an automatic i switch operating as a finder tohunt for and connect with a calling line and operating as a connectorunder directive control to connect with and test a called line. for itsbusy or idle condition, means in the switch operated responsive to theestablishment of a connection with an idle called line for applyingsignalling current to the line, and means in the switch operatedresponsive to the establishment of a connection with a busy called linefor preventing the operation of said last means until the called linebecomes idle.

4. In a telephone system, an {automatic switch operating as al finder tohunt for and connect with a calling line in outgoing calls and operatingas a connector under directive control of an operator in incoming callsto connect with and test a called line for its busy or idle condition,means in the switchoperated responsive to the establishment of aconnection with an idle called line for applying signalling currentthereto, and means in the switch operated responsive to theestablishment of a connection with a busy called lin'e for applying adistinctive tone thereto to notify the subscribers of the waiting call.

5. In a telephone system, two exchanges, a trunk line connecting saidexchanges, a switch terminating said trunk line at one exchange, saidswitch operating to hunt for and connect with a calling subscribers lineand operating under directive control of an attendant at said oneexchange to connect with and test a called subscribers line, means inthe switch operated responsive to the extension of a connection to abusy called line for establishing a temporary talking connection betweenthe called line and the attendant, means controlled by the attendant forcausing said switch to remain in connection with the busy line while theattendant withdraws from the connection, means responsive to the calledline becoming idle for signallingI the line, and means responsive to thesubscriber answermg for connecting the called line with the trunk line.

6. A telephone system as claimed in claim 5 in which the switcheffecting the connection with the called subscribers line restores tonormal position responsive to the called subscriber replacing hisreceiver to terminate the call.

7. In a telephone system, a switch equipped with a pair of line wipersand a test wiper, called lines accessibleI to the switch via saidwipers, means for operating the switch to establish a connection with acalled line, a relay for restoring the switch to normal position, andmeans for operating said relay over a circuit including one of said linewipers.

8. In a telephone system, a switch equipped with a pair of line wipersand a test wiper, a home position for the switch, means for operatingthe switch from home position to establish a talking connection with acalled line via said line wipers, a relay for stepping the switch, asecond relay for controlling said first relay, means for operating thesecond relay over a circuit including one of said line wipers, and meanscontrolled by said second relay for marking the home position of saidswitch to prevent said rst relay from stepping the switch after the homeposition is reached.

9. In a telephone system, a main exchange and a branch exchange, a trunkline connecting said exchanges, a switch terminating said trunk line atthe branch exchange, means for operating said switch as a iinder inbranch to main exchange calls, means for operating the switch as aconnector in main to branch exchange calls, and means controlled over abranch exchange subscribers line for restoring the switch to normalresponsive to the termination of a call of either class.

10. In a telephone system, a main exchange and a branch exchange, anattendants switchboard at the branch exchange, a trunk line extendingfrom the main exchange through said switchboard to a switch in` thebranch exchange, means for operating said switch as a exchange, acalling device including a pair of impulse contacts at the switchboard,means for connecting said calling device to either said local trunk lineor to said switch, and means for adapting the calling device to transmitimpulses over a single conductor to operate said switch or to transmitimpulses over the two conductors of said local trunk line in series tooperate switches associated with said trunk line.

l2. In a. telephone system, two exchanges connected by a trunk line, aswitch terminating the trunk line at one exchange, an attendantsswitchboard at said one exchange, means at the switchboard fordirectively operating said switch to extend a call incoming over thetrunk line to a called subscribers line in said one exchange, means inthe switch for testing the called line for its idle or busy condition, arelay in the switch operated responsive to the called line testing idlefor applying signalling current to the line, a second relay in theswitch operated responsive to the called line testing busy forpreventing-the operation of said lirst relay, a third relay forpreventing the release of the switch when the attendant withdraws fromthe connection, means controlled by the attendant for operating saidthird relay, and means controlled byvsaid third relay for lockingoperated under control of said second relay.

. 13. A telephone system as claimed in claim 12 in which the second andthird relays release upon the busy called line becoming idle and thefirst relay operates to apply signalling current to the line.

14. In a telephone system comprising al main exchange and a branchexchange, subscribers lines in the branch exchange, a twoway trunk lineconnecting the exchanges, a switch terminating said trunk line at thebranch exchange and having access to said lines, means for operatingsaid switch to c0nnect with a calling line or with an idle or busycalled line, means in the switch for immediately connecting a calling orbusy called line with said trunk, and means in the switchVA for delayingthe connection of an idle called line with the trunk until the calledsubscriber answers the call.

15. In a telephone system comprising a main exchange and a branchexchange, subscribers lines in the branch exchange, a twoway trunk lineconnecting the exchanges, a switch terminating the trunk line at thebranch exchange, means for operating said switch to connect with acalling or called line, means in the switch ,for connecting the linewith said trunk line, means for signalling the line prior to theoperation of said connecting means when a call is extended to an idlevcalled line, and means for delaying the operation of said signallingmeans until the line becomes idle when a call is extended to a busycalled line.

AIn testimony whereof we aiix our signatures.

CHARLES EDMUND BEALE. HERBERT STANLEY DEYES.

